<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>边框</title>
    <style>
        .c1 {
            width: 200px;
            height: 100px;
            /*background: red;*/
            /*border-left-color: red;*/
            /*border-left-style: groove;*/
            /*border-left-width: 30px;*/
            /*border-right-color: green;*/
            /*border-right-style: ridge;*/
            /*border-right-width: 30px;*/
            /*border-top-color: blue;*/
            /*border-top-style: inset;*/
            /*border-right-width: 30px;*/
            /*border-bottom-color: purple;*/
            /*border-bottom-style: outset;*/
            /*border-bottom-width: 30px;*/
            /*border-left: red 20px solid;*/
            /*border-right: green double 20px;*/
            /*border-top: blue dashed 20px;*/
            /*border-bottom: purple dotted 20px;*/
            /*border-style: solid double dashed dotted;*/
            /*border-width: 20px;*/
            /*border-color: red green blue purple;*/
            border: 10px dashed red;
        }

        .c2 {
            width: 220px;
            height: 100px;
            background: green;
            border-radius: 10%;
        }
        .c3{
            width: 200px;
            height: 200px;
            background: yellow;
            border-radius: 50%;
            border: 100px solid;
            border-color: red green blue purple;
        }
    </style>
</head>
<body>
<div class="c1"></div>
<hr>
<div class="c2"></div>
<hr>
<div class="c3"></div>
</body>
</html>